Changes in the ability to smell and taste can be caused by a simple cold or upper respiratory tract infection, but they may also be among the first signs of neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Now, new research from the Perelman School of Medicine at the University of Pennsylvania has revealed an association between an impaired sense of smell and myasthenia gravis (MG), a chronic autoimmune neuromuscular disease characterized by fluctuating fatigue and muscle weakness. The findings are published in the latest edition of PLOS ONE.